The use of dispensers to disperse water treatment compositions, typically chemical compositions, into bodies of water, such as swimming pools and spas, is long known. Typically these dispensers have either floated on top or just beneath the surface of water, or have been employed in the flow loop of forced circulation systems, e.g., skimmer type dispensers placed within the pool filter system. Dispensers are used with fast dissolving chemicals, such as calcium hypochlorite, and slower dissolving chemical systems containing trichloroisocyanurate.
In many floating dispensers, the upper end of the housing of the device is circumscribed by a buoyant material so that the device floats in an upright orientation with its upper end above the water line when placed in a pool. One or more openings are provided at the lower end of the housing to allow water to enter the housing, dissolve the tablets, and provide a flow of a solution that disinfects and otherwise treats the water, for example, a stream of halogen solution that disinfects and otherwise treats the water.
In operation, the size, number, or path length of water-admitting openings in the housing control the water flow through the device and the dose is managed by selecting an appropriate amount of the chemical formulation, often tablets, which are placed inside the housing. The device is placed in the body of water, e.g., pool or spa, water circulates through the opening or openings in the lower end of the housing, the water treatment dissolves and is dispensed throughout the body of water until the entire water treating chemical has dissolved.
While simple in design and operation, difficulties can be encountered when using these devices. For example, many of these floating devices provide no indication when the amount of water treatment has been fully dissolved or dispersed. It is also possible that the openings through which the dissolved water treatment must flow become plugged, slowing or stopping dispersion of the desired treatment into the pool. Further, although dispensers are known which will signal when the water treatment has been fully or mostly dispersed, in many cases the visual signal can be difficult to detect without careful examination or is provided in an inelegant way which compromises the aesthetics of the device. For example, one known floating chemical dispenser signals complete dissolution of the treatment by having a buoyant housing list over to one side.
U.S. Pat. No. 8,007,664, the disclosure of which is incorporated herein by reference, discloses a dispenser which has a floating bucket for carrying a solid, dissolvable water treatment chemical, which bucket is connected to a set of tabs which become visible as the chemical dissolves and the bucket floats higher in the water.
U.S. Pat. No. 5,662,795, the disclosure of which is incorporated herein by reference, discloses a skimmer-basket type chemical dispenser which includes a buoyant colored plate within a cylindrical container that floats to the top when all of the chemical is dissolved. However, the resulting visual signal (i.e. the portion of the plate visible through a top-mounted dispenser opening) is visible only within a narrow, vertical cone circumscribing a central axis of the cylindrical container and such a signaling mechanism would be ineffective in a floating dispenser located in a central portion of the pool, as the signal generated would be difficult if not impossible to see from a side angle. Typically, dispensers in the prior art provide no signal to show that the device is working properly.
While it has been common to associate dispensers such as pool dispensers with chlorine sources such as hypochlorite salts and chloroisocyanurates, a variety of other water treatments can be added through a dispenser, including non-halogen oxidizers, pH altering agents, flocculants and so on. Often, more than one type of chemical agent can be used at a time. U.S. Pat. No. 7,560,033, incorporated herein by reference, discloses a stable, solid, anhydrous composition comprising an oxidizing agent, i.e. Oxone® which is a source of potassium peroxymonosulfate, and an active halogen agent, e.g., a salt of dichloro-s-triazine trione. Note: Oxone® and compounds containing halides or active halogens can form a dangerous combination capable of releasing harmful amounts of chlorine gas.